First of all space, I have a ton of console because I enjoy games, and every console I buy has a different selection. Second having a backup. Consoles don't last forever, my PS1 broke but I can still play the games on my PS2. I would like to be able to continue to play them without having to look around at pawn shops to find another one that isn't covered in filth. Third is saves you money than having to buy the rerelease to play it on your modern console if you just want to keep one console.